White Bengal tiger cubs are pictured in the Xantus Janos Zoo of Gyor, 120 kms west of Budapest, Hungary, Thursday, February 19, 2015. The two cubs were born on Jan. 19, but their mother did not care for them, so the zoo keepers have to feed and raise them. (Photo by Csaba Krizsan/AP Photo/MTI)

White Bengal tiger cubs are pictured in the Xantus Janos Zoo of Gyor, 120 kms west of Budapest, Hungary, Thursday, February 19, 2015. (Photo by Csaba Krizsan/AP Photo/MTI)

Polar bear twins make their first public appearance with their mother “Freedom” at Ouwehands Zoo Rhenen, in Rhenen, The Netherlands, 19 February 2015. The twins, who were born in November 2014, have not been named because their gender has not yet been determined. (Photo by Bart Maat/EPA)

A polar bear mother helps her cubs get out of the water as they venture outside their enclosure for the first time since they were born at Ouwehands Zoo in Rhenen, Netherlands, Thursday, February 19, 2015. Three cubs were born Nov. 22, 2014 but one of the triplets died soon after birth, the cub's mother and grandmother live at the zoo, their father now lives at the Yorkshire Wildlife Park in England. (Photo by Peter Dejong/AP Photo)

Two polar bear cubs follow their mother as they venture outside their enclosures for the first time since they were born at Ouwehands Zoo in Rhenen, Netherlands, Thursday, February 19, 2015. (Photo by Peter Dejong/AP Photo)

A snarling response from Sumatra tiger Tess as she clutches tightly onto her lunch while being observed by visitors at Burgers' zool in the town city of Arnhem February 17, 2015. (Photo by Koen van Weel/EPA)

Huskies compete during the Trans-Thuringia race, one of the biggest dog-sled races with purebred dogs in central Europe, in the Thuringian Forest near Fehrenbach, central Germany, Saturday, February 14, 2015. Around 500 sled dogs and their mushers covered a distance of nearly 280 kilometers in seven runs. (Photo by Jens Meyer/AP Photo)

Musher Stefan Wagner competes with his dog-sled during the Trans-Thuringia race, one of the biggest dog-sled races with purebred dogs in central Europe, in the Thuringian Forest near Fehrenbach, central Germany, Saturday, February 14, 2015. (Photo by Jens Meyer/AP Photo)

Musher Dieter Bruening competes with his dog-sled during the Trans-Thuringia race, one of the biggest dog-sled races with purebred dogs in central Europe, in the Thuringian Forest near Fehrenbach, central Germany, Saturday, February 14, 2015. (Photo by Jens Meyer/AP Photo)

A three-toed sloth (Bradypus Variegatus) named Coquito is seen crawling during his rehabilitation at the Panamerican Conservation Association (APPC) on the outskirts of Panama City February 13, 2015. The APPC found Coquito in the city outside of his habitat, and said he was orphaned due to urbanization. The Associaton conducts wildlife rescue and rehabilitation in support of the National Environmental Authority of Panama, caring for and relocating hundreds of sloths and other animals back into their habitat. (Photo by Carlos Jasso/Reuters)

A two toed sloth (Choloepus hoffmanni) named Corey is seen during her rehabilitation at the Panamerican Conservation Association (APPC) on the outskirts of Panama City February 13, 2015. (Photo by Carlos Jasso/Reuters)

A trainer does exercises with white whales at the temporary enclosure of an oceanarium at Russky Island in the far eastern city of Vladivostok, February 17, 2015. Prosecutors in Primorsky Krai last week launched an investigation into the death of at least six sea animals and fish at the local oceanarium where construction was stalled as a result of a corruption scandal, local media reported. The oceanarium was supposed to be completed by the time of the Asia Pacific Economic Cooperation forum in Vladivostok in September 2012. (Photo by Yuri Maltsev/Reuters)

White whales swim in their temporary enclosure at an oceanarium at the Russky Island in the far eastern city of Vladivostok, February 17, 2015. (Photo by Yuri Maltsev/Reuters)

A walrus looks out of its enclosure at an oceanarium at Russky Island in the far eastern city of Vladivostok, February 17, 2015. (Photo by Yuri Maltsev/Reuters)

A sea lion looks out of its enclosure at an oceanarium at Russky Island in the far eastern city of Vladivostok, February 17, 2015. (Photo by Yuri Maltsev/Reuters)

Sandbar sharks swim around during a cageless shark dive tour in Haleiwa, Hawaii February 16, 2015. Shark tours are a renowned form of eco-tourism in Hawaii and diving with sharks without a cage is becoming increasingly popular as well. (Photo by Hugh Gentry/Reuters)

Dogs wait to be sold at a street pet dog market in Lanzhou, Gansu province, February 15, 2015. Picture taken February 15, 2015. (Photo by Aly Song/Reuters)

A seagull sits at the observation deck of the historical Galata tower with snow-covered Karakoy district and the Bosphorus in the background in Istanbul February 19, 2015. (Photo by Murad Sezer/Reuters)

In this February 13, 2015 photo provided by the San Diego Zoo Safari Park, a four-week-old male okapi calf explores his outdoor habitat for the first time at the Park in Escondido, Calif. The young okapi, the 41st born at the Park and named Amaranta, previously had been spending time in the okapi barn and outside yard, but after showing signs of curiosity, staff provided the calf and his mother, Makini, access to the main forested habitat, which is viewable by guests. The okapi, a relative of the giraffe, is native to rainforests of central Africa. The Safari Park has taken a leadership role in conservation awareness through its ongoing support of the Okapi Conservation Project, which provides wildlife protection, alternative agriculture methods and community assistance in the Democratic Republic of Congo. (Photo by AP Photo/San Diego Zoo Safari Park)

Mouth of a hippopotamus seen wide open while it eats carrots on February 18, 2015 at Whipsnade Zoo, England. (Photo by Tony Margiocchi/Barcroft Media)

In this Tuesday, February 17, 2015, photo, flamingoes at the Memphis Zoo huddle together for warmth in Memphis, Tenn. Low temperatures gripped the South on Wednesday, refreezing the snow and ice and making roads hazardous. (Photo by Jim Weber/AP Photo/The Commercial Appeal)

Parma wallaby baby “Norman” who was born mid September 2014 is nurtured by animal keeper Yvonne Wicht with a bottle of milk at the ZOO in Krefeld, Germany, 18 February 2015. The baby was rejected by his mother after birth. While they work, the animal keepers carry “Norman” around in a fabric bag tied around their belly. At night, Yvonne Wicht takes her fosterling back to her own home. Around midnight, “Norman”, who weighs 1040 gramm now, is fed for the last time a day. (Photo by Horst Ossinger/DPA/ZUMA Wire)

An undated handout picture made available by the Taronga Conservation Society Australia on 20 February 2015 shows a rare newborn antelope at Taronga Zoo, Sydney, Australia. The calf, an Eastern Bongo, was born on 08 February 2015 to mother Djembe and father, Ekundu. (Photo by EPA/Taronga Zoo)

A red panda cub rests on a snowy perch in an outdoor habitat at the Knoxville Zoo, Wednesday, February 18, 2015, in Knoxville, Tenn. Most of east Tennessee is under winter weather advisories and wind chill warnings that could last throughout the week. (Photo by Amy Smotherman Burgess/AP Photo/Knoxville News Sentinel)

A new-born cotton-top tamarin sits on the shoulder of its mother at the zoo in Duisburg, Germany, Friday, February 20, 2015. (Photo by Martin Meissner/AP Photo)

A white-cheeked gibbon watches the photographer at the zoo in Duisburg, Germany, Friday, February 20, 2015. (Photo by Martin Meissner/AP Photo)

A female white-cheeked gibbon baby watches its father at the zoo in Duisburg, Germany, Friday, February 20, 2015. (Photo by Martin Meissner/AP Photo)

Baby gorilla Diara explores its enclosure at the Zoo in Leipzig, Germany, Tuesday, February 17, 2015. Diara was born in March 2014. (Photo by Jens Meyer/AP Photo)

Penguins dressed in Chinese traditional costumes walk at Harbin Polar Land decorated with Chinese Lunar New Year theme in Harbin in northeast China's Heilongjiang province Monday, February 16, 2015. Workers dressed up six gentoo penguins in the park to celebrate the Lunar New Year on coming Feb. 19 this year which marks the Year of the Sheep on the Chinese zodiac. (Photo by AP Photo)

A pygmy hippopotamus named Ayoka chews on a branch at the zoo in Duisburg, Germany, 20 February 2015. Pygmy hippopotamus are the smaller “cousins” of the common hippopotamus, weighing around 250 kilogrammes in average. (Photo by Roland Weihrauch/EPA)

A confiscated gecko, caged inside a plastic bottle, is displayed during a press conference at Suvarnabhumi Airport in Bangkok, Thailand, 20 February 2015. Thai customs arrested two Japanese male passengers identified as Toshikazu Kawai, 39, and Naoki Hiraguchi, 39, for the alleged attempt to smuggle 110 Pignose Turtles, four Woodchuck, 21 snakes, and nine geckos, all found inside their suitcases upon their departure from Bangkok to Nagoya, Japan. The smuggled wildlife were listed as endangered species in the Convention on International Trade in Endangered Species (CITES). (Photo by Rungroj Yongrit/EPA)

Baby orangutan Rieke is held by a zoo keeper at the Berlin Zoo in Berlin, Germany, 18 February 2015. Rieke's days in the capital are numbered as on 23 February she is leaving the zoo in Berlin and moving to the English Dorset. (Photo by Paul Zinken/EPA)